Process for Making precision tweezers with tips attached to the tines

ABSTRACT

A process is described for making a set of precision tweezers ( 1 ) which includes a grip ( 2 ) with two tines ( 2′, 2″ ), to each of which is attached a shaped tip ( 3′, 3″ ), characterized by the fact that it includes the following phases:  
     a) said grip ( 2 ) is constructed by making one or more through holes ( 4 n) at the end of each tine ( 2′, 2″ );  
     b) a single mold ( 5 ) is constructed that reproduces both said shaped tips ( 3, 3′ );  
     c) at least said ends of two tines ( 2′, 2″ ) of the grip are introduced into said mold ( 5 ), and they are locked in the position in which said shaped tips ( 3′, 3″ ) are to be attached to said tines ( 2′, 2″ );  
     d) a synthetic resin is injected by die casting into mold  5,  in such a way that it forms said two shaped tips ( 3, 3′ ), surrounding the ends of said two tines ( 2, 2′ ) and encompassing them, and, in the process, said holes ( 4   n ) that are made in them are tamped.

[0001] This invention pertains to the field of technology that deals with the production of precision tweezers and, in particular, it refers to the sector thereof that is devoted to the production of precision tweezers that are made up of a grip and two tines, to whose ends tips are attached that are shaped in such a way as to be able to perform their specific functions.

[0002] The idea of attaching tips to a grip makes it possible, as one skilled in the art knows, first to produce the shaped tips with greater precision and accuracy since they are used to form the grip and, secondly, to make the shaped tips out of materials that are different from those used for the grip and that have completely different physical characteristics. It is not uncommon, for example, to encounter cases where a metal grip that has optimum bending strength and elevated fatigue resistance is equipped with shaped tips made of synthetic resin that are attached to the ends of its two tines.

[0003] By properly selecting the type of synthetic resin, it is possible to make said tips in a way that is better suited to the kinds of operations that they are intended to perform.

[0004] According to the current state of the art, known shaped tips are attached to the ends of the tines by threaded or other means that make it possible to align them accurately with the axes of the tines.

[0005] One such attachment method is described in patent U.S. Pat. No. 5,899,513 of this claim.

[0006] Moreover, these methods require positioning operations that are very precise and are therefore quite costly in order to produce such attachment means with the absolute minimum of errors and/or tolerances, but they do not achieve the best possible results in terms of precision owing to the fact that, at times, cumulative errors that are present in the various parts that are to be assembled build up in a set of tweezers.

[0007] The inventor of this invention has therefore devised a process that makes it possible to reduce to a minimum the inaccuracies involved in the production of precision tweezers, thereby limiting the costs of the necessary operations.

[0008] The inventor has devised a process that is new because, as far as he is aware, said synthetic-resin tips are mated by means of die-casting, covering the two ends of the tips that are inserted into a single mold and are firmly attached thereto.

[0009] The object of this invention is a process for making precision tweezers as described in the preamble to attached claim 1, characterized by the content of said same claim.

[0010] Another object of the invention is precision tweezers that can be produced by the process of the invention.

[0011] A more detailed description will now be given of a preferred embodiment of the process of the invention, but said example is neither binding nor limiting with regard to other implementations of the process that one skilled in the art could implement based on the teachings of said claim 1.

[0012] In this description reference will be made to the attached drawings, where:

[0013]FIG. 1 shows a schematic of the longitudinal section of a mold in which the shaped tips and tines of a set of precision tweezers according to the invention are mated;

[0014]FIG. 2 shows a top view of the single grip of the precision tweezers of FIG. 1;

[0015]FIG. 3 shows a side view;

[0016]FIG. 4 shows a top view of a set of precision tweezers after the shaped tips are attached;

[0017]FIG. 5 shows a side view.

[0018]FIGS. 2, 3 show how a grip 2 produced according to known methods encompasses two appropriately designed tines 2′, 2″ at whose ends, according to the process of the invention, two through holes 4 n are made (clearly, the number of said holes 4 n can vary, depending on requirements).

[0019]FIG. 1 shows then how said grip 2 is inserted into a mold 5 that reproduces two shaped tips 3′, 3″, at the exact locations where the tips themselves are to be attached thereto.

[0020] By pouring into mold 5, by the known technique of die-casting, a synthetic resin in the liquid state through one or more inlets 6, 7, said resin forms two shaped tips 3′, 3″, encompassing the two ends of tines 2′, 2″ and flowing through said holes 4 n, in such a way that shaped tips 3, 3′ wind up being perfectly positioned with respect to grip 2 and are firmly connected to it because of passing through above-mentioned holes 4 n.

[0021] This produces a set of precision tweezers with all of the elements that comprise it in exactly the right locations, and does so through a single molding operation, thereby achieving the goals that the inventor had set himself.

[0022] To implement the process of the invention and to produce the precision tweezers that can be obtained thereby, it is possible to use all of the synthetic resins that are known to one skilled in the art and that have physical-chemical characteristics that are best suited to their specific functions.

[0023] The inventor further suggests that shaped tips 3, 3′ be made of a polymer or copolymer synthetic resin that may be “charged” with fibers that alter its physical characteristics.

[0024] In order to obtain shaped tips 3, 3′ with optimum mechanical resistance and good resistance to abrasion, it is possible to use, e.g., polymer or copolymer resins that are charged with glass fibers, while to make shaped tips 3, 3′ that are especially well-suited for operations to be carried out on electrical and/or electronic circuits, even those under voltage, the inventor suggests that a polymer or copolymer resin charged with carbon fibers and/or carbon powder be used so as to make the resin “dissipative”, i.e., slightly conductive in order to discharge it without sparks from electrostatic charge and/or electric current.

[0025] The ideal resistivity value that is to be imparted to the material of said shaped tips are made should, according to the inventor, be around 10⁷- 10⁹ ohm. 

1. Process for making a set of precision tweezers (1) , which includes a grip (2) with two tines (2′, 2″), to each of which is attached a shaped tip (3′, 3″), characterized by the fact that it includes the following phases: a) said grip (2) is constructed by making one or more through holes (4 n) at the end of each tine (2′, 2″); b) a single mold (5) is constructed that reproduces both said shaped tips (3, 3′); c) at least said ends of two tines (2′, 2″) of the grip are introduced into said mold (5), and they are locked in the position in which said shaped tips (3′, 3″) are to be attached to said tines (2′, 2″); d) a synthetic resin is injected into mold 5 by die casting, in such a way that it forms said two shaped tips (3, 3′), surrounding the ends of said two tines (2, 2′) and encompassing them, and, in the process, said holes (4 n) that are made in them are tamped.
 2. Process according to claim 1 , wherein said synthetic resin is of the dissentive type.
 3. Process according to claim 2 , wherein said synthetic resin is a polymer or copolymer resin, and said die-testing is carried out at a temperature of 270-280° C.
 4. Process according to claim 3 , wherein said synthetic polymer or copolymer resin is charged with glass fibers in order to enhance its mechanical resistance.
 5. Process according to claim 3 , wherein said synthetic polymer or copolymer resin is charged with carbon fibers and/or carbon powder so as to produce an electrical resistivity value of between 10⁷-10⁹ ohm.
 6. Precision tweezers (1) that can be produced by means of the process according to one of the previous claims, wherein they include a grip (2) with two tines (2′, 2″), at the ends of which there are one or more holes (4 n), whereby two shaped tips (3, 3′) of the tweezers are made with a die-cast synthetic resin that totally encompasses shaped tips (3, 3′) by passing through said holes (4 n). 